con <- dbConnect(
MySQL(),
user = "username", password = "password",
host = "<my amazon web service database server>",
port = 3306
)

dbDisconnect(dbListConnections(MySQL()))

dbListConnections(MySQL())
[[1]]TRUE

Error in .local(dbObj, ...) :
internal error in RS_DBI_getConnection: corrupt connection handle

(I query the database to generate this output):
internal error in RS_DBI_getConnection: corrupt connection handle

con <- dbConnect(
  MySQL(),
  ...
)

MyFunction <- function(){
  myQuery <- paste("SELECT * FROM ...")
  df <- dbGetQuery(con, myQuery)
  df
}

MyFunction <- function(){

  con <- dbConnect(
    MySQL(),
    ...
  )

  myQuery <- paste("SELECT * FROM ...")
  df <- dbGetQuery(con, myQuery)

  dbDisconnect(con)
  df
}